D-chiro-Inositol-containing compounds were abundant in common laboratory animal feed. By gas chromatography-mass spectrometry (GC/MS) of 6 N HCI hydrolysates, Purina Roden Chow 5001 contained 0.23% of D-chiro-inositol by weight. The principal sources were alfalfa and soybean meal whereas other chow ingredients had less than 2% as much per gram as these legumes. Only traces of L-chiro-inositol were found. D-chiro-Inositol was present in a water-soluble non-ionic form of which most was shown to be pinitol, 1D-3-O-methyl-chiro-inositol. More than 98% of the D-chiro-Inositol fed to rats as Purina Rodent Chow 5001 as well as purified pinitol and deuterated D-chiro-Inositol tracer was absorbed from the gastrointestinal tract. Rats chronically ingesting the chow diet consumed 921 (mol of total D-chiro-inositol/kg/day and excreted less than 5% of that amount in the stool and urine suggesting that the bulk was metabolized. However, even though urinary excretion of total D-chiro-i nositol was very small compared to intake, it declined further by over 98% in response to a chiro-inositol-deficient diet. Thus, urinary levels may reflect dietary intake. Recent reports have shown that D-chiro-inositol is found in certain putative insulin mediator fractions and that increased urinary excretion occurs in uncontrolled diabetes mellitus. Further work is needed to clarify the dietary and potential nutritive role of D-chiro-inositol.